JP2005218017A - Coding device and method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable efficiently performing coding according to a photographing mode. <P>SOLUTION: An coding device has: a photographing mode selecting unit (115) for switching a plurality of photographing modes; a flesh color detecting processing unit (103) for detecting predetermined colors on the basis of previously set color information; coding means (105-108, 111, 112) for coding image data; and control means (114, 104) for controlling the code quantity of the image data to be coded by the coding means on the basis of a photographing mode selected by the photographing mode selecting means and of a region of predetermined color detected by the color detecting means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an encoding apparatus and method, and more particularly to an image encoding apparatus and method capable of changing the encoding processing method.

  FIG. 5 is a block diagram showing an image encoding device using a conventional technique. In FIG. 5, reference numeral 501 includes a lens and an image sensor, and an imaging unit that captures a subject. 502 is an image signal processing unit that executes a series of image signal processing such as gamma conversion, color space conversion, and raster-block conversion. A skin color detection processing unit for detecting the face portion of a person who is generally high in importance as a subject to be photographed, and 504 encodes an input image that has been block-interleaved. An image encoding processing unit that compresses the code amount, 505 is a recording unit that records encoded data on a recording medium such as a magnetic tape or a memory card, and 506 is operated by a photographer to perform shooting for setting a shooting mode. It is a mode selection part.

  The encoded data output from the image encoding processing unit 504 generally differs in encoding method between still image shooting and moving image shooting. At the time of still image shooting, the JPEG method standardized by ISO (International Organization for Standardization) is widely used as an encoding method for storing and displaying a still image on a storage medium such as a CD-ROM or a hard disk. In addition, the MPEG standard standardized by ISO is widely used as an encoding method for saving and displaying on a similar storage medium, broadcasting via a communication channel, or two-way communication when shooting moving images. .

  Shooting modes that can be selected and set by the shooting mode selection unit 506 include, for example, a sport mode suitable for shooting a subject moving at high speed, and a spot suitable for shooting a subject that is exposed to strong light in a dark room or the like. There are a light mode, a surf & snow mode suitable for shooting outdoors with strong sunlight, and a portrait mode suitable for shooting a person's face.

  The sports mode is a shooting mode in which a fast-moving subject can be shot sharply without blurring by increasing the shutter speed in a fast-moving sports scene such as a running person. The spotlight mode is a shooting mode that enables shooting with an appropriate exposure without overexposure when shooting a scene illuminated with a spotlight such as a stage or a wedding hall. The surf & snow mode is a shooting mode that prevents a subject from appearing dark even in a bright background such as the seaside or a slope, and enables shooting with appropriate exposure. The portrait mode is a shooting mode in which it is possible to shoot with a shallow subject depth and a blurred background so that only a person stands up.

  When the photographer selects and sets these shooting modes with the shooting mode selection unit 506, the intention of shooting can be reflected in the image data output from the image signal processing unit 502 (see, for example, Patent Document 1). ).

JP 05-137147 A

  However, in the conventional image coding apparatus, the photographer's intention is reflected in the image data output from the image signal processing unit 502 by selecting and setting the shooting mode. Regardless of the shooting mode, the input data of the still image and the moving image is subjected to the code amount control process under the same conditions without being reflected in the control process.

  The present invention has been made in view of the above problems, and an object of the present invention is to enable more efficient encoding in accordance with a shooting mode.

  In order to achieve the above object, an encoding apparatus according to the present invention includes a shooting mode selection unit that switches a plurality of shooting modes, a color detection unit that detects a predetermined color based on preset color information, and image data. The image data encoded by the encoding means on the basis of the encoding mode selected by the imaging mode selection means and the area of the predetermined color detected by the color detection means. Control means for controlling the amount of code.

  The encoding method of the present invention includes a shooting mode selection step for switching a plurality of shooting modes, a color detection step for detecting a predetermined color based on preset color information, and an encoding for encoding image data. And a control for controlling a code amount of the image data encoded in the encoding step based on a shooting mode selected in the shooting mode selection step and a predetermined color area detected in the color detection step Process.

  According to the above configuration, encoding can be performed more efficiently according to the shooting mode.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is a block diagram showing a configuration of an image coding apparatus according to the first embodiment of the present invention. In FIG. 1, reference numeral 101 denotes an image pickup unit that includes a lens and an image pickup device, and shoots an image. Reference numeral 102 denotes an image signal processing unit that executes a series of image signal processing such as gamma conversion, color space conversion, and raster-block conversion. A skin color detection processing unit 104 is used for the purpose of detecting the face portion of a person who is generally highly important as a shooting target with respect to an image that has been subjected to image processing, and 104 is an arbitrary region of the shot image data Is a filter unit that selectively attenuates the high-frequency component intensity, 105 is a motion compensation prediction unit that predicts a reference image block that most closely matches the prediction target image block and generates a motion vector, and 106 is a discrete cosine transform or the like An orthogonal transform unit that performs orthogonal transform, 107 is a quantizer that divides the orthogonal transform coefficient by a quantization matrix and reduces the amount of information, and 108 is variable by a Huffman code or the like An entropy encoding unit that further reduces the amount of information by encoding, 109 is a buffer unit that smoothes the amount of code generated per unit time that fluctuates on the time axis, and 110 is a recording medium such as a magnetic tape or a memory card A recording unit 111 for recording the encoded data in the unit 111, an inverse quantization unit for inversely quantizing the orthogonal transform coefficient quantized by the quantization unit 107 in order to reconstruct the reference image, and 112, an inverse quantization unit 111 Is an inverse orthogonal transform unit that performs inverse orthogonal transform on the orthogonal transform coefficient after inverse quantization generated by, 113 is a shooting mode selection unit that is operated by the photographer to set the shooting mode, and 114 is an occupancy rate of the buffer unit 109. A control unit 115 that monitors and controls the encoded data so that it does not overflow or become empty, is operated by a photographer, and an encoding mode for selecting a still image or a moving image. A selection unit.

  First, in the image encoding apparatus having the above-described configuration, a flow until image data captured when the moving image encoding mode is selected by the encoding mode selection unit 115 is recorded as encoded data is illustrated in FIG. This will be briefly described with reference to FIG.

  The image data input from the image pickup unit 101 is subjected to a series of image signal processing such as gamma conversion, color space conversion, and raster-block conversion in the image signal processing unit 102 in accordance with the shooting mode set by the shooting mode selection unit 113k. Applied. Then, the skin color detection processing unit 103 performs skin color detection processing on the image subjected to a series of image processing for the purpose of detecting particularly a face portion of a person who is generally high in importance as a photographing target, and as a result. The control unit 114 can adaptively perform the code amount control by controlling the quantization unit 107 and the filter unit 104 by using.

  Furthermore, the motion compensation prediction unit 105 predicts a reference image block that most closely matches the prediction target image block, and generates a motion vector. Thereafter, after a series of encoding processes are performed by the orthogonal transform unit 106, the quantization unit 107, and the entropy encoding unit 108, the encoded data is temporarily stored in the buffer unit 109, and finally stored in the magnetic unit by the storage unit 110. Or a recording medium such as a memory card. While writing to the magnetic tape is performed at a constant data rate, the rate of the encoded data output from the entropy encoding unit 108 is not constant. Therefore, the control unit 114 controls the quantization unit 107 to perform encoding. Data is prevented from overflowing from the buffer unit 109 or conversely becoming empty.

  On the other hand, in order to generate a reconstructed image used in the motion compensation prediction unit 105, the orthogonal transform coefficient quantized by the quantization unit 107 is inversely quantized by the inverse quantization unit 111, and further by the inverse orthogonal transform unit 112. Inverse orthogonal transform is performed.

  As described above, when the face portion of a person who is generally high in importance as a photographing target can be recognized by the skin color detection process, the code amount control unit 112 performs quantization step values when quantizing the image block corresponding to the face portion. Can be reduced to increase the amount of information, and an encoding process can be performed in which a good result is obtained in the visual psychological model.

  Next, skin color detection processing performed by the skin color detection processing unit 103 under a normal shooting environment will be briefly described with reference to FIG.

  FIG. 2A shows one image extracted from a moving image sequence in which a person is photographed under a normal photographing environment. FIG. 2B shows an example of the result of the skin color detection process performed by the skin color detection processing unit 103 on the image of FIG. 2A, and the area recognized as the skin color is shown as a black area. . The face portion of the person in FIG. 2A is recognized as the skin color, and the skin color detection result is accurate.

  Next, the code amount control processing in the quantization unit in the first embodiment of the image coding apparatus having the above configuration will be described with reference to the flowchart of FIG.

  When the photographing start is instructed by the photographer (step S101), the control unit 114 checks the encoding mode set in the encoding mode selection unit 115 (step S102). When the encoding mode is the moving image encoding mode, the process proceeds to step S103, and the shooting mode set in the shooting mode selection unit 113 is checked.

  In step S103, when the shooting mode is not the portrait mode (NO in step S103), the process ends.

  On the other hand, if the shooting mode is the portrait mode in step S103 (YES in step S103), the process proceeds to step S104, and the quantization is performed when the image block corresponding to the area detected as the skin color in the skin color detection processing unit 103 is quantized. The code amount is increased by reducing the conversion step value. In addition to this control, when quantizing an image block corresponding to a region other than the region detected as skin color, the quantization unit 107 is controlled so as to reduce the code amount by increasing the quantization step value. May be. As a result, the quantization unit 107 is controlled so that the code amount for the region detected as the skin color in the skin color detection processing unit 103 is relatively increased as compared with the other regions.

  By the code amount control processing by the control unit 114 described above, the code amount in the region where the presence of the skin color shown in FIG. 2B is detected increases, while the code amount in the other regions decreases. In the portrait mode selected by the user, the depth of field is reduced and the background is blurred so that only a person can stand up. Therefore, the amount of code is effectively reduced while reflecting the user's intention, and visual Even in the psychological model, it is possible to perform a code amount control process that provides a good result.

  As described above, according to the first embodiment, it is possible to reduce the amount of code to be recorded while improving the image quality, thereby saving the capacity of the recording medium and recording more images for a longer time. It becomes possible to do.

  In the first embodiment, the case where the quantization step value used in the quantization unit 107 is changed in order to control the coding amount has been described. However, the present invention is not limited to this, and the coding amount is not limited thereto. Any coding condition may be controlled as long as it can be changed.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described. Note that the configuration of the image coding apparatus according to the second embodiment is the same as that described with reference to FIG. 1 in the first embodiment, and a description thereof will be omitted.

  The code amount control processing in the quantization unit in the second embodiment of the image coding apparatus having the above configuration will be described with reference to the flowchart of FIG. The process shown in FIG. 4 is performed by the control unit 114 on the filter unit 104 according to the shooting mode.

  When the start of shooting is instructed by the photographer (step S201), the control unit 114 checks the coding mode set in the coding mode selection unit 115 (step S202). When the encoding mode is the moving image encoding mode, the process proceeds to step S203 to check the shooting mode set in the shooting mode selection unit 113, and when it is not the moving image encoding mode, the process ends.

  If the photographing mode is not the portrait mode in step S203, the process is terminated. If the portrait mode is present, the high frequency component intensity is applied to the image input data other than the area detected as the skin color by the skin color detection processing unit 103. The filter unit 104 is controlled to attenuate (step S204).

  The code amount control processing by the control unit 114 described above reduces the code amount in the region other than the portion where the presence of the flesh color shown in FIG. 2B is detected. However, in the portrait mode selected by the user, only the person is present. Since the subject depth is so shallow that the background is blurred and the background is blurred, the code amount can be effectively reduced while reflecting the user's intention, and good results can be obtained even in the visual psychological model. Control processing can be performed.

  As described above, according to the second embodiment, since the amount of code to be recorded can be reduced while improving the image quality, the capacity of the recording medium can be saved, and more images can be recorded for a longer time. It becomes possible to do.

  Needless to say, the first and second embodiments can be implemented in combination.

  In the first and second embodiments, the process for changing the skin color detection area is executed only in the moving image encoding mode. However, the present invention is not limited to this, and is executed in the still image encoding mode. You may make it.

  In addition, the present invention is not limited to the control based on whether or not the skin color region is used, but it is also possible to detect a desired color and control the code amount based on the detection result.

<Other embodiments>
Note that the present invention can be applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a scanner, a video camera, etc.), or a device (for example, a copier, a facsimile device, etc.) composed of a single device. You may apply to.

  Another object of the present invention is to supply a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded to a system or apparatus, and the computer (or CPU or CPU) of the system or apparatus. Needless to say, this can also be achieved by the MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included. Examples of the storage medium for storing the program code include a flexible disk, hard disk, ROM, RAM, magnetic tape, nonvolatile memory card, CD-ROM, CD-R, DVD, optical disk, magneto-optical disk, MO, and the like. Can be considered. Also, a computer network such as a LAN (Local Area Network) or a WAN (Wide Area Network) can be used to supply the program code.

  Furthermore, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card or the function expansion unit performs part or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

  When the present invention is applied to the above-mentioned storage medium, the program code corresponding to the flowchart shown in FIG. 3 and / or FIG. 4 described above is stored in the storage medium.

It is a block diagram which shows the structure of the image coding apparatus in embodiment of this invention. It is a figure explaining the skin color detection process example in a normal imaging environment. It is a flowchart of the code amount control process in the 1st Embodiment of this invention. It is a flowchart of the code amount control process in the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the image coding apparatus using a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Image pick-up part 102 Image signal processing part 103 Skin color detection processing part 104 Filter part 105 Motion compensation prediction part 106 Orthogonal transformation part 107 Quantization part 108 Entropy encoding part 109 Buffer part 110 Recording part 111 Inverse quantization part 112 Inverse orthogonal transformation part 113 Shooting mode selection unit 114 Control unit 115 Encoding mode selection unit

Claims (20)

A shooting mode selection means for switching between a plurality of shooting modes;
Color detection means for detecting a predetermined color based on preset color information;
Encoding means for encoding image data;
Control means for controlling the code amount of the image data encoded by the encoding means based on the shooting mode selected by the shooting mode selection means and the predetermined color area detected by the color detection means; An encoding apparatus comprising:   2. The encoding unit according to claim 1, wherein the encoding unit performs encoding in accordance with a preset encoding condition, and the control unit controls a code amount by changing the encoding condition of the encoding unit. The encoding device described in 1.   3. The control unit according to claim 2, wherein the control unit performs control so as to change the encoding condition so that a code amount of the region of the predetermined color is relatively larger than a code amount of the other region. The encoding device described in 1. The encoding means comprises quantization means;
The encoding apparatus according to claim 2 or 3, wherein the encoding condition is a step amount at the time of quantization by the quantization means. The control means includes attenuation means for attenuating high frequency components of image data,
The attenuation means attenuates high-frequency components in areas other than the predetermined color based on the shooting mode selected by the shooting mode selection means and the area of the predetermined color detected by the color detection means. The encoding device according to any one of claims 1 to 4. The shooting mode includes a person shooting mode mainly for shooting a person,
The encoding apparatus according to claim 1, wherein the control unit controls a code amount when a person photographing mode is set.   The encoding apparatus according to claim 6, wherein the color information is color information indicating a skin color, and the color detection unit detects a skin color. Further comprising encoding mode selection means for switching a plurality of encoding modes for encoding an image;
8. The encoding apparatus according to claim 1, wherein the control unit further controls a code amount in accordance with an encoding mode selected by the encoding mode selection unit. The plurality of encoding modes include a still image encoding mode and a moving image encoding mode,
The control means does not control the code amount when the still image encoding mode is selected, and controls the code amount when the moving image encoding mode is selected. 8. The encoding device according to 8. A shooting mode selection step for switching between multiple shooting modes;
A color detection step of detecting a predetermined color based on preset color information;
An encoding process for encoding image data;
A control step of controlling a code amount of the image data encoded in the encoding step based on the shooting mode selected in the shooting mode selection step and a predetermined color area detected in the color detection step; An encoding method comprising:   The encoding step performs encoding according to a preset encoding condition, and the control step controls the amount of code by changing the encoding condition used in the encoding step. Item 11. The encoding method according to Item 10.   12. The code according to claim 11, wherein, in the control step, the coding condition is changed so that a code amount of the region of the predetermined color is relatively larger than a code amount of the other region. Method. The encoding step includes a quantization step;
The encoding method according to claim 11 or 12, wherein the encoding condition is a step amount at the time of quantization in the quantization step. The control step includes an attenuation step for attenuating high frequency components of the image data,
In the attenuating step, high frequency components in regions other than the predetermined color are attenuated based on the photographing mode selected in the photographing mode selecting step and the predetermined color region detected in the color detecting step. The encoding method according to claim 10. The shooting mode includes a person shooting mode mainly for shooting a person,
The encoding method according to any one of claims 10 to 14, wherein, in the control step, a code amount is controlled when a human photographing mode is set.   The encoding method according to claim 15, wherein the color information is color information indicating a skin color, and the skin color is detected in the color detection step. A coding mode selection step of switching a plurality of coding modes for coding an image;
The encoding method according to any one of claims 10 to 16, wherein, in the control step, a code amount is further controlled according to the encoding mode selected in the encoding mode selection step. The plurality of encoding modes include a still image encoding mode and a moving image encoding mode,
The control step includes controlling the code amount when the still image encoding mode is selected, and controlling the code amount when the moving image encoding mode is selected. 18. The encoding method according to 17.   A program executable by an information processing apparatus, comprising program code for realizing the encoding method according to claim 10.   20. A storage medium readable by an information processing apparatus, wherein the program according to claim 19 is stored.

Images